The present invention will be referred to as being in relation to a manufacturing method suitable for making multi-layer boards. While reference throughout the specification should be made to use of the present invention in relation to corrugated paperboards, it should be appreciated that the principles of the present invention can be applied to materials other than paper and configurations other than corrugations.
Single face corrugated paperboard is very well known and is used extensively in the industry, especially in packaging where it is used as protective padding and wrapping. It is also used as the basic components in the production of many structural objects such as boxes, panels, pallets, etc.
Sheets of single face corrugated paperboard can be bonded together to form multi-layer corrugated paperboards of various thicknesses and strength. One reason for the wide use of such paperboard is that it is relatively lightweight and has considerable rigidity and strength.
Single face corrugated paperboard is usually made by bonding a fluted sheet, typically of corrugating medium (generally recycled paper) onto a liner sheet. The liner sheet is typically Kraft paper although other materials may be used.
However, in typical manufacturing process the boards are made such that the flute troughs and peaks are positioned substantially horizontally. This means that weight bearing on the surface of the board can act to flatten out the corrugations or flutes and crush the board. Therefore, it will be desirable if there could be found a manufacturing process that enables the board to be used in such a way that greater strength could be obtained.
One method by which this can be achieved can be to have multiple layers of boards, however there are considerable problems associated with ensuring that the layers of board are held together. Due to the fragile nature of the boards, the layers cannot merely be pressed together via friction fit or some other mechanical means. Instead, chemical bonding is required in the form of the application of an adhesive between the layers.
In order to be effective, the adhesive needs time to cure. Unfortunately, when it is desired to have a rapid production process, this curing time represents a significant bottleneck in the production process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.